Effect of Temperature on Total Resonance Absorption of Neutrons by Spheres of Uranium Oxide

In the expression 1/α=c[1+(κ/ρR)] for the advantage (α) of decreased resonance absorption of uranium in a dE/E neutron spectrum brought about by lumping UO₂ into spheres, the temperature dependence of c is measured and κ is measured also. ρ is the density of UO₂ in g/cm³; R the radius of the sphere in cm. In the range 20° to 1000°C, Δc/ΔT averages 1.8×10⁻⁶ per degree centigrade and is positive as expected. This temperature dependence decreases by about a factor of three from the lowest to the highest measured temperatures. κ is 5.06 g/cm³ leading to a value of μ in the expression [Phys. Today 5, 32 (May, 1952)] $${\left({\displaystyle \int }\mathrm{\sigma (E)}\frac{\mathrm{dE}}{E}\right)}_{\mathrm{eff}}\mathrm{=A}\left[\text{1+μ}\frac{S}{M}\right]$$ of 1.69 g/cm². $$\frac{\mathrm{\Delta A}}{\mathrm{\Delta T}}\hspace{0.17em}\mathrm{is}{\text{\hspace{0.17em}4×10}}^{\text{−4}}\frac{\mathrm{barns}}{{}^{\circ }\mathrm{C}}$$ .